"No person shall be under any duty, whether by contract or by any statutory or other legal requirement, to participate in any treatment authorised by this act to which he has a conscientious objection."

This is modified by another clause, which states that it does not apply in cases of emergency, where the mother's life is at stake. It has also been modified by a later case in which a doctor's secretary, a devout Roman Catholic, refused to type letters referring women for abortions. She lost her case, which went all the way to the House of Lords, on the grounds that typing and sending a letter was not "participating in any treatment".

That looks unsatisfactory to some philosophers. If I have a conscientious objection to the death penalty, I might well refuse to transmit a death sentence to a place where it would be put into effect because I felt that by doing so I was participating in the execution. But that is how the law now stands.

There isn't any similar exemption for stem-cell research.

Their lawyer, Neil Addison, who sometimes writes here, added a new twist to this protection. He claimed that the nurses' "belief in the sanctity of life from conception onwards was a philosophical belief protected under the Equality Act and therefore any attempt to pressure them into participating in the abortion clinic or to suggest that their refusal would affect their career would be illegal under the Equality Act 2010."

This argument has not been tested in court, but it would be entirely fascinating if it were.

Defenders of the present situation would claim that it is enormously unwise and tyrannical for a government to presume to override the conscience of any individual. We allow conscientious objectors in war; why not in peacetime? Opponents will surely claim that we can't allow just anything to be claimed as a conscientious right. There are people who believe it is their religious duty to smoke immense quantities of marijuana. The law dismisses this opinion. Why should it take more account of the opinions of Roman Catholics?

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